No other vehiclar engine, other than a Stirlingtype power plant, requires both a crank motor and blower motor for starting a cold engine. Both motors demand an auxiliary power source and the cold engine does not produce sufficient power output to energize the blower until a stable level of operating conditions is achieved. The requirement for separate and distinct motors has proved to be a disadvantage since both must be arranged separately and each constitute a duplication in weight and structure for the engine and promote an additional drain upon the engine battery. Space limitations imposed on automotive engine packaging are difficult to meet with the use of two separate motors.
The motors, when operated, overlap during their time of functioning. For example, a typical starting sequence for a Stirling engine comprises (a) starting the blower motor (by using an auxiliary power source) to clear the system of residual gases, (b) after an interval of four seconds, fuel and spark are injected into the system, (c) after an operating temperature of 600.degree. C is sensed in the heater chamber, the crank motor is started by an auxiliary power source, (d) after 400 r.p.m. is achieved by the output number of the engine, the crank motor is cut out, and (e) after an operating temperature of about 675.degree. C is obtained in the heater chamber, the blower motor is cut out with the blower being driven directly by the engine. It can be appreciated that between the temperatures of 600.degree.-675.degree. C both motors may be functioning if the engine r.p.m. is under 400. The control for the crank motor requires both predetermined levels of temperature and speed to permit cut out; below such levels, frictional drag and inertia are too great to be overcome by the engine to sustain motion. The overlapping functioning of such motors usually requires the incorporation of transmission systems and overrunning devices to eliminate interference therebetween.